1. Field of the Invention
The present invention relates to a seat construction for motor vehicles, and more particularly to a vehicle seat of the type having a backrest member hinged to a seat squab member to be tilted forwardly or backwardly with respect to the seat squab member.
2. Discussion of the Prior Art
In Japanese Utility Model Laid-open Publication No. 1-77533 and Patent Laid-open Publication No. 60-21710, there has been proposed a vehicle seat of the type which includes a seat squab frame, a backrest frame hinged for angular adjustment relative to the seat squab frame, and a strut member connected at its opposite ends to an upper end of the backrest frame at one side thereof and to one side of the scat squab frame. The strut member acts as a reinforcement member to resist an excessive forward force acting on the backrest frame in the occurrence of vehicle collision. To enhance the reinforcement function of the strut member, it is advantageous that the lower end of the strut member is connected to the one side of the seat squab frame at a position displaced as forwardly as possible.
However, if the lower end of the strut member was displaced forwardly, the strut member would become an obstacle to ingress or egress of a passenger from the vehicle seat. To avoid such a problem, the strut member of the vehicle seat disclosed in the former Laid-open Publication No. 1-77533 is in the form of a support mechanism composed of three support rods mutually connected in a truss construction, wherein the joint portion of the support rods is arranged at one side of the backrest to facilitate ingress or egress of a passenger from the vehicle seat. The support mechanism is, however, complicated in its construction and causes undesired movements at the mounting portions of the support rods.
The strut member of the vehicle seat disclosed in the latter Laid-open Publication No. 60-21710 is in the form of a pair of support rods telescopically connected to one another, wherein one of the support rods is connected at its lower end to one side of the seat frame while the other rod is connected to an upper end of the backrest frame at one side thereof, and wherein one of the support rods is provided with a locking mechanism which cooperates with a reclining mechanism of the vehicle seat. When the reclining mechanism is released from its locked condition to permit forward or backward movement of the backrest, the locking mechanism is released to permit relative movement of the supports rods. When the reclining mechanism is locked to retain the backrest at an adjusted position, the locking mechanism is locked to firmly connect the support rods to one another. However, the support rods become an obstacle to ingress or egress of the passenger from the vehicle seat. Since the locking mechanism is arranged to be interlocked with the reclining mechanism, the operability of the reclining mechanism is deteriorated.